When round stock is to be machined, it is seated in a V-block to provide adequate support therefor. It is, however, necessary that the V-block be centered with respect to the tool element if the machining is to be centered relative to the center of the workpiece.
It will be readily apparent that it is difficult to align a V-block by eye with respect to the tool element. Accordingly, there has been desired some simple means by which alignment of the apex of the V-block with the tool element can be assured.